linux-kernel - Re: [PATCH V2 7/8] vfio/pci: Support dynamic MSI-x

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <cc84101a-b6d1-c33d-d7a8-115f846c358c@intel.com>
Date:   Tue, 4 Apr 2023 13:46:01 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Alex Williamson <alex.williamson@...hat.com>
CC:     "Tian, Kevin" <kevin.tian@...el.com>,
        "jgg@...dia.com" <jgg@...dia.com>,
        "yishaih@...dia.com" <yishaih@...dia.com>,
        "shameerali.kolothum.thodi@...wei.com" 
        <shameerali.kolothum.thodi@...wei.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "darwi@...utronix.de" <darwi@...utronix.de>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "Liu, Jing2" <jing2.liu@...el.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        "tom.zanussi@...ux.intel.com" <tom.zanussi@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 7/8] vfio/pci: Support dynamic MSI-x

Hi Alex,

On 4/4/2023 11:43 AM, Alex Williamson wrote:
> 
> I think Kevin has a point, if it's correct that we do this get/write in
> order to account for manipulation of the device since we wrote into the
> vector table via either pci_alloc_irq_vectors() or
> pci_msix_alloc_irq_at(), then it really only makes sense to do that
> restore if we haven't allocated the irq and written the vector table
> immediately prior.  Thanks,
> 

I see. Even so, could it be acceptable to call get_cached_msi_msg()/pci_write_msi_msg()
unconditionally (for MSI-X) or should the new [1] vfio_pci_alloc_irq()
indicate if a new IRQ was allocated to determine if 
get_cached_msi_msg()/pci_write_msi_msg() should be run?

Reinette


[1] https://lore.kernel.org/lkml/20230403211841.0e206b67.alex.williamson@redhat.com/